JPH09291228A - Reflection-inhibiting coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition forming a slight amount of hardly soluble layer, having a low reflective index and forming an interference- inhibiting film of good quality on a photoresist film, comprising a perfluoroalkyl sulfonic acid, an organic amine and polyvinylpyrrolidone, etc. SOLUTION: This reflection-inhibiting coating composition contains (A) a perfluoroalkyl sulfonic acid, (B) an organic amine, (C) polyvinylpyrrolidone, (D) a water-soluble alkylsiloxane polymer and water. Preferably, a compound expressed by Cn F2n+1 SO3 H ((n) is 5-10) is used as the component A, ethanolamine is used as the component B and molecular weight of the component C is 1,000-10,000, and a compound expressed by the formula (R<1> to R<4> are each H, OH or CH3 , etc.; (n') is 1-10; (m) is 1-20) is used as the component D, and 1 pt.wt. of the component C, 2-7 pts.wt. of the component A, 0.2-1 pt.wt. of the component B, 0.001-0.10 pt.wt. of the component D and 5-100 pts.wt. of water are respectively used in the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for an antireflection coating, and more particularly, to interference with light reflected from a substrate in a photoresist film when forming a pattern by a photolithography technique using a photoresist. The present invention relates to an antireflection coating composition for forming an anti-interference film on a photoresist film for preventing a decrease in pattern dimensional accuracy (variation in pattern dimensional width).

[0002]

2. Description of the Related Art Generally, a semiconductor device is manufactured by forming a photoresist film on a substrate such as a silicon wafer, selectively irradiating it with an actinic ray, and then performing a developing treatment to form a photoresist pattern on the substrate. A lithography technique for forming is applied.

By the way, as mentioned above, it is known that when the photoresist film is selectively irradiated with an actinic ray, the pattern dimension width varies due to the interference effect. Therefore, various studies have been made everywhere to minimize the variation in the pattern dimension width. Some of them are, for example, JP-A-5-188598, JP-A-6-69120, and JP-A-6-148896.

The above is a composition for antireflection coating formed on a photoresist film, which comprises a water-soluble polymer binder and a water-soluble fluorocarbon compound (perfluorocarboxylic acid, quaternary ammonium salt of perfluorosulfonic acid, etc.). Is disclosed. Moreover, a transparent film having a refractive index of 1.401 is obtained from this composition, and when actually applied to a photolithography process, as compared with the case where there is no antireflection coating film,
It is said that variations in sensitivity due to variations in photoresist film thickness will be reduced. The variation in sensitivity is due to the multiple interference effect of light in the resist film, and the ideal refractive index of the antireflection film is √ (N resist) = 1.28 to 1.30.

The above discloses a method of forming a fine resist pattern in the step of applying an alkali-controlled antireflection film on a positive photoresist containing naphthoquinonediazide and a novolac resin. The antireflection film herein contains a water-soluble polymer such as polyvinyl alcohol-based, polyacrylic acid-based, or polyvinylamine-based, and the pH is adjusted to about 10 with an organic alkali such as tetramethylammonium hydroxide. Further, the refractive index of this resist antireflection layer is adjusted by a polymer containing fluorine or a surfactant containing fluorine. In this example, since the antireflection film is applied on the positive resist, the naphthoquinonediazide and the novolac resin contained in the positive resist surface cause a crosslinking reaction by using the alkali contained in the antireflection film as a catalyst to cause the resist surface. Is being changed to a poorly soluble substance. As a result, the film loss of the positive photoresist is suppressed, and in addition, in this method, ARCOR is used.
Since the method is adopted, the dimensions of the resist pattern are said to be stable.

Further, in the above, by providing a resist coating solution containing a water-soluble film forming component and a fluorine-based surfactant, and an interference preventing film made of the coating solution on the resist surface, the pattern dimensional accuracy is improved. It is to form an excellent resist pattern. The water-soluble film-forming component here is an acrylic acid-based polymer or polyvinylpyrrolidone which is a water-soluble polymer having no hydroxyl group in the molecule, while the fluorine-based surfactant is a perfume.
Examples are fluorocarboxylic acids, perfluorosulfonic acids or their respective quaternary ammonium salts.

[0007]

However, in the above description, when the antireflection film is formed on the resist, an undeveloped layer (insolubilized layer) may occur in the upper layer portion of the resist pattern after the development. This phenomenon is considered to be because the novolak resin as a resist component and the naphthoquinonediazide compound interact with each other due to the presence of the quaternary ammonium salt, and the surface portion becomes insoluble in the developing solution. In reality, it is still far from the ideal refractive index. The above method has a drawback that it can be applied only to a positive photoresist containing naphthoquinonediazite and a novolac resin. Furthermore, the only R _f COOH is the insoluble in water (base for the first time to dissolve exist), R _f CO
In the case of OM and R _f SO ₃ M (M is a quaternary ammonium compound), there is a drawback that a poorly soluble layer is formed on the resist surface.

An object of the present invention is to solve the above-mentioned drawbacks and to provide an antireflection coating composition for forming a good quality anti-interference film on a photoresist film.

[0009]

[Means for Solving the Problems] The inventors of the present invention have been researching and studying antireflection and coating liquids for a long time, and for the antireflection coating mainly consisting of perfluoroalkylcarboxylic acid and organic amine. A composition was proposed (Japanese Patent Application No. 7-131096). However, in the subsequent study, this composition sometimes causes shrinkage of the film thickness in the baking process after forming the coating film on the resist, and the degree of this shrinkage largely depends on the baking temperature and the baking time. I found out that In addition, since such a phenomenon is that perfluoroalkylcarboxylic acid, which is a weak acid, and organic amine, which is a weak base, are mixed, the mutual bonding force is weak, and the energy of baking (heat) treatment causes the perfluoroalkylcarboxylic acid to react. It is considered that the bond between the acid and the organic amine was broken and a part of the organic acid was volatilized.

Therefore, an antireflection film was experimentally produced by using perfluoroalkylsulfonic acid which is a strong acid in place of perfluoroalkylcarboxylic acid. As a result, unlike the combination of the perfluoroalkylcarboxylic acid and the organic amine, the antireflection film coated on the resist showed almost no shrinkage of the film thickness due to the baking treatment. In addition, as for the refractive index, the refractive index for light in the short wavelength region (light wavelength near 436 nm to 248 nm) is lower than that of the combination of perfluoroalkylcarboxylic acid + organic amine + water-soluble polymer. There is. The present invention has been made based on this.

According to the present invention, (1) perfluoroalkylsulfonic acid, organic amine, polyvinylpyrrolidone,
(2) A composition for antireflection coating comprising a water-soluble alkyl siloxane polymer and water, (2) In the above (1), perfluoroalkylsulfonic acid is a compound represented by the following general formula (I) C _n F _{2n + 1} SO ₃ H ... (I) (n = 5 to 10) Compound represented by the formula, (3) The above (1)
In (4), the organic amine is monoethanolamine,
In the above (1), polyvinylpyrrolidone has a molecular weight of 1,000 to 10,000, preferably 2,000 to 5,000.
(5) In the above (1), the water-soluble alkyl siloxane polymer has the following general formula (II):

Embedded image (R ¹ , R ² , R ³ and R ⁴ may be the same or different and are —H, —OH, —CH ₃ or —O (CH ₂ CH ₂ O).
Representing mH, n ′ = 1 to 10 and m = 1 to 20. )
A composition for an antireflection coating, which is a compound represented by:

Further, according to the present invention, (6) in the above (1), when the weight ratio of the composition is 1 for polyvinylpyrrolidone, perfluoroalkylsulfonic acid is 2
To 7 preferably 3 to 6, organic amine 0.2 to 1 preferably 0.2 to 0.6, water soluble alkyl siloxane polymer 0.001 to 0.10 preferably 0.01 to 0.0.
8. The composition for antireflection coating, characterized in that water is 50 to 100, (7) In the above (6), the blending ratio of polyvinylpyrrolidone and perfluoroalkylsulfonic acid is from 1: 3 by weight. The composition for antireflection coating is 1: 5, and the blending ratio of polyvinylpyrrolidone and the organic amine is 1: 0.3 to 1: 0.5 in weight ratio, (8) The above (6) ),
There is provided a composition for an antireflection coating, wherein the water-soluble alkyl siloxane polymer accounts for 0.001 to 0.5% of the total composition.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. Perfluoroalkyl sulfonic acid used in the present invention is preferably those represented by the general formula _{(I) C n F 2n +} 1 SO 3 H (n = 5~10), among others C ₈ F ₁₇ SO ₃ H Is preferably used. This perfluoroalkyl sulfonic acid is used as an activator and is insoluble in water, but it has a property of being dissolved in the presence of a basic substance.

Polyvinylpyrrolidone has the following properties required for a water-soluble polymer binder: (i) good coating performance during spin coating, (ii) good compatibility with fluorosurfactants, and (iii) high temperature baking. Processing (150-1
It has good solubility in water after about 60 ° C.) and (iv) low refractive index.

The polyvinylpyrrolidone used in the present invention has a molecular weight of 1,000 to 10,000, preferably 2,000.
~ 5000. If the molecular weight is less than 1000, it is difficult to obtain a uniform film quality, and if it is more than 10,000, there is a tendency that threading during spin coating or coating film failure occurs.

In the relationship of perfluoroalkylsulfonic acid (activator) / polyvinylpyrrolidone ratio, the larger the proportion of the activator, the lower the refractive index, which is advantageous. However, on the other hand, when the blending ratio of perfluoroalkylsulfonic acid to polyvinylpyrrolidone is increased, the surface condition after film formation becomes rough, crack-like patterns occur, or the time after film formation is increased. Due to
The appearance of particles on the surface appears, and crystalline protrusions occur.

According to a study by the present inventors, surface roughness and
It was found that the composition ratio of perfluoroalkyl sulfonic acid and organic amine is greatly involved in the generation of cracks, and that the additive can suppress the increase of particles and the generation of crystalline protrusions. . Regarding the relationship between the composition ratio of perfluoroalkyl sulfonic acid and the organic amine, there is a relationship as shown in Table 1 of the results of Example 3 described later (a favorable tendency is recognized in the combination in the thick line). In the composition of the combination within the thick line in Table 1, the surface roughness and the crack-like pattern are less likely to occur, and the increase of particles and the degree of generation of protrusions are small.

However, the optimization of the composition alone cannot sufficiently suppress the increase of particles and the generation of protrusions when the blending amount of perfluoroalkylsulfonic acid increases. In addition, there are lactose and xylose compounds as additives that suppress such a phenomenon, but the addition of these compounds increases the refractive index and is not preferable as an additive for the antireflection film. As a result of intensive studies, it was found that the addition of the water-soluble alkyl siloxane polymer can form an antireflection film that does not increase the refractive index and does not increase particles or generate protrusions. In addition, the blending of perfluoroalkyl sulfonic acid tends to have a higher contact angle when dropped on the resist as compared with perfluoroalkylcarboxylic acid, and it may be difficult to apply depending on the underlying resist material. As a countermeasure against this, by adding an amount of alcohol that does not damage the resist film, the contact angle on the resist film can be lowered and a uniform coating film can be formed.

The water-soluble alkyl siloxane polymer used in the present invention is represented by the general formula (II), and there are commercially available products such as polyflo-KL-245 (manufactured by Kyoeisha Yushi Co., Ltd.). The water-soluble alkyl siloxane polymer is added in an amount of 0.001 to 0.10 parts by weight, preferably 0.01 to 0.08 parts by weight, per 1 part by weight of polyvinylpyrrolidone.
If it is less than 0.001 part by weight, the effect due to addition is poorly expressed, and conversely if it is more than 0.10 part by weight, precipitation may occur.

Embedded image

As mentioned above, perfluoroalkylsulfonic acid is dissolved in the presence of a basic substance, but the basic substance used in the present invention is an organic amine, and among them, alkanolamine, especially monoethanolamine is used. desirable. Therefore, in the present invention, the combination of perfluoroalkylsulfonic acid, polyvinylpyrrolidone, organic amine, water-soluble alkyl siloxane polymer and water gives a uniform and stable film quality having a lower refractive index, and also on the resist. The formation of the hardly soluble layer does not occur.
Water can be added in any amount, but polyvinylpyrrolidone 1
It is preferable to add 50 to 100 parts by weight with respect to parts by weight, and this water is preferably pure water (ion-exchanged water).
Is used.

[0021]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The parts here are based on weight.

Example 1 1 part of polyvinylpyrrolidone having a molecular weight of 3000, 4 parts of perfluorooctane sulfonic acid, and 2-aminoethano-
Solution (0.35 parts) and water-soluble alkyl siloxane polymer (0.004 parts) of Polyflo-KL-245 (produced by Kyoeisha Yushi Co., Ltd.) were dissolved in pure water (94.646 parts) to give 0.05 μm.
What was filtered through the m filter was prepared as an antireflection coating composition. Positive photoresist (made by Hoechst, AZ
-7800) is applied to prepare a wafer. The film thickness of the resist is about 100Å in the range of 1.0 to 1.5 μm.
Prepare ones that have been changed one by one. After applying the resist, the antireflection coating composition prepared in this example is applied so that the film thickness on the resist is approximately 650Å. After that, baking is performed at 90 ° C. for 90 seconds,
After exposure by an i-line stepper, baking is performed at 110 ° C. for 90 seconds, development processing is performed for 60 seconds with a 2.38% TMAH developing solution, and sensitivity is measured for each film thickness. The fluctuation range of the sensitivity due to the standing wave effect is about that of the case where the antireflection film according to the present embodiment is applied, compared with the case where the antireflection film is not used (when the relative fluctuation range of the case where the antireflection film is not used is 100). , The effect of decreasing to 23 was recognized.
The refractive index of the antireflection film at this time was 1.395 with respect to light having a wavelength of 365 nm. Furthermore, even after 7 days had passed since the antireflection film was formed, no crystal-like formation or alteration of the film was observed.

Example 2 An anti-reflection coating composition prepared by adding 5 parts of isopropyl alcohol to 100 parts of the anti-reflective coating composition of Example 1 was used in the same manner as in Example 1 to prepare AZ-78.
00 was coated on a coated wafer, the coating state at that time was observed, and at the same time, the dependency of the sensitivity on the resist film thickness was evaluated. As a result, as for the coating property of the antireflection coating composition on the resist, the addition of isopropyl alcohol improves the wettability on the resist (decreases the contact angle) and improves the coating performance. In addition, as a characteristic of the antireflection film of the present invention example, a value of 1.392 was obtained for the light having a wavelength of 365 nm as the refractive index of the film. Furthermore, even after 7 days had passed since the antireflection film was formed, no crystal-like formation or alteration of the film was observed. Furthermore, the film thickness dependence of the sensitivity is 2 at a relative ratio almost the same as in Example 1.
A value of 4 was obtained.

Comparative Example 1 The composition is the same as that prepared in Example 1 except that the water-soluble alkylsiloxane polymer of Polyflo-KL-245 (manufactured by Kyoeisha Yushi Co., Ltd.) was omitted. The refractive index of the antireflection film is 36.
A value of 1.392 was obtained for light with a wavelength of 5 nm. Further, the film thickness dependence of the sensitivity is 2 at a relative ratio almost the same as in Example 1.
A value of 4 was obtained. However, after the antireflection film was formed on the wafer and two days passed, crystal-like formation was observed in the film.

Example 3 A fixed amount of 0.005 parts of a water-soluble alkyl siloxane polymer of Polyflo-KL-245 (Kyoeisha Yushi Co., Ltd.) was fixed, and monoethanolamine (MEA) with respect to polyvinylpyrrolidone and perfluorooctane sulfone. Acid (C
Table 1 shows a list comparing the characteristics when the compounding ratio of ₈ F ₁₇ SO ₃ H) was changed. Each composition ratio in Table 1 is a blending weight ratio when polyvinylpyrrolidone (PVP) 1 is used.

[0026]

[Table 1]

[0027]

According to the invention of claim 1, an antireflection coating composition having a low refractive index, which can reduce the formation of a poorly soluble layer and can form a layer on which no particles or crystals are formed, can be formed. Is obtained. According to the inventions of claims 2 to 8, it is possible to obtain an antireflection coating composition that exhibits the above effects more effectively.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/027 H01L 21/30 574

Claims (8)

[Claims] 1. An antireflective coating composition comprising perfluoroalkyl sulfonic acid, an organic amine, polyvinylpyrrolidone, a water-soluble alkylsiloxane polymer and water. 2. The antireflection coating according to claim 1, wherein the perfluoroalkylsulfonic acid is a compound represented by the following general formula: C _n F _{2n + 1} SO ₃ H (n = 5 to 10). Composition. 3. The antireflection coating composition according to claim 1, wherein the organic amine is monoethanolamine. 4. The polyvinylpyrrolidone has a molecular weight of 1
It is 000-10000, The composition for antireflection coatings of Claim 1 characterized by the above-mentioned. 5. The water-soluble alkyl siloxane polymer has the following general formula: (R ¹ , R ² , R ³ and R ⁴ may be the same or different and are —H, —OH, —CH ₃ or —O (CH ₂ CH ₂ O).
Representing mH, n ′ = 1 to 10 and m = 1 to 20. )
The composition for antireflection coating according to claim 1, which is a compound represented by: 6. A weight ratio of the composition is 2 to 7 for the perfluoroalkylsulfonic acid, 0.2 to 1 for the organic amine, and 0 for the water-soluble alkylsiloxane polymer, where polyvinylpyrrolidone is 1 by weight. 0.001-0.10, 5 water
It is 0-100, The composition for antireflection coatings of Claim 1 characterized by the above-mentioned. 7. The blending ratio of the polyvinylpyrrolidone and the perfluoroalkylsulfonic acid is 1: in a weight ratio.
7. The antireflection coating composition according to claim 6, wherein the composition is 3 to 1: 5, and the mixing ratio of the polyvinylpyrrolidone and the organic amine is 1: 0.3 to 1: 0.5 in a weight ratio. Stuff. 8. The blending amount (weight) of the water-soluble alkyl siloxane polymer in the entire composition is 0.001 to 0.
It is 5%, The composition for antireflection coatings of Claim 6 characterized by the above-mentioned.